N2O reduction during denitrifying phosphorus removal with propionate as carbon source
Cong Li1, Qian Wang2, Wenlin Jia3
1School of Environmental and Programming, Liaocheng University, Liaocheng, 252059, Shandong, China.
Summary
Using propionate as a carbon source significantly reduced nitrous oxide (N2O) emissions during denitrifying phosphorus removal, unlike acetate. This reduction is linked to lower nitrite accumulation and microbial community differences.
Area of Science:
- Environmental Engineering
- Microbiology
- Wastewater Treatment
Background:
- Denitrifying phosphorus removal is crucial for wastewater treatment.
- Nitrous oxide (N2O) is a potent greenhouse gas often produced during denitrification.
- Carbon source selection impacts nutrient removal and N2O emissions.
Purpose of the Study:
- To investigate the effect of different carbon sources (acetate, propionate, mixed) on nutrient removal and N2O production in sequencing batch reactors.
- To identify factors influencing N2O generation during biological nutrient removal.
Main Methods:
- Sequencing batch reactors (SBRs) were operated with distinct carbon sources.
- Nutrient removal efficiencies (nitrogen and phosphorus) were monitored.
- Nitrous oxide (N2O) emissions and emission factors were quantified.
- Microbial community composition was analyzed.
Main Results:
- Propionate resulted in significantly lower nitrogen removal (40.6% less) but comparable phosphorus removal to acetate.
- N2O production was substantially reduced with propionate (0.43% emission factor) compared to acetate (16.3%) and mixed sources (1.9%).
- Acetate systems showed enrichment of ordinary heterotrophic organisms (glycogen-accumulating organisms), correlating with higher N2O production.
Conclusions:
- Propionate is a more favorable carbon source for minimizing N2O emissions in denitrifying phosphorus removal systems.
- Lower nitrite accumulation in propionate-fed systems is the primary driver for reduced N2O production.
- Microbial community structure plays a role in N2O generation during biological nutrient removal.
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